PIC 18f14k50 running from input port power?

[johanfo]

Hi,

I have a quick question I didn't find the answer to on the internet, nor in the documentation.

I have a PIC 18f14k50 up and running. To my big surprise, when I disconnected Pin1 (Vdd), the unit kept running. Obviously from the power of one of the I/O ports configured as Input (Pin9 to be specific).

Now, is this expected behaviour, or have I seriously misconfigured something?

JF

 

[Pretest]

Probably that the power goes back to the Vdd pin through the protection diodes. If you measure the voltage on Vdd, it should be (Vdd - Vdiode).

 

[johanfo]

You are a smart cookie! There was a 0.87v difference (Vdd was 0.87v lower than the input-port) as you predicted!